does it also create better fuel consumption than an engine without power valve?

Thats partially wrong. It dont causes exhaust backpressure, which is regulated over silencer inner diameter. The valve changes GAS EXCHANGE TIMING, which causes change in compression, and much more...

​@@herrderkolbenringeyeah that's what the video was trying to explain it's still hard to understand fully though because they don't really explain much I'm assuming it's because these guys who made this video don't really speak English

@@herrderkolbenringe Es geht darum die Strömungsgeschwindigkeit zu optimieren richtig? Ähnlich wie wenn ich einen zu klein/großen vergaser fahre würde

This system like Vtec for 2 stroke engine...I have old Kawasaki with KIPS system, that more efficient than yamaha, because KIPS system are not electronic.

"Old tech now" ? Only because 2-strokes aren't prevelant today. The ones still around still use power valves.Yamahas YPVS, Hondas ATAC, Kawasaki KIPs and Suzukis whatever it was called.after

@@holdernewtshesrearin5471 I meant old as in invented a long time ago, certainly not old as in obsolete! 😉

@@mrsilbo6499 - gotcha.

perhaps we should introduce a powervalve on the intake side as well, now that 2 strokes are seeing a revival with fuel injection.

@@holdernewtshesrearin5471 ktm have much better now and i don´t mean thats electric but shape and direction how it is opening

Yamaha patented the power valve in 1977 & all the Japanese manufacturers had their own versions - Kawasaki's KIPS, Honda's ATAC, Suzuki's AETC, so the list is endless.

@@mrsilbo6499 YPVS, RC VALVE, AETC has same model they use Bridgeport different with Kawasaki KIPS they use 2 small port in the side of exhaust port or actually it's called power valve but in KX125 it's combine Bridgeport with KIPS. Sorry for bad english

@@Alvon_PR It has to be different to the YPVS setup, otherwise there would be patent infringement! Thank you for sharing the details. 👍

@@mrsilbo6499 my favourite weird name is from rotax - The RAVE (Rotax Adjustable Variable Exhaust) todays kids can relate to this .. hahaha

@@mohba01 Brilliant! 😄

not really.. guillotine power valve/blades are common on rotax, suzuki, ducati/cagiva, Minarelli and many engines since the 90's. Yamaha stopped making the cylindrical "cotton reel" design running across the top of the exhaust port using the servo motors in the late 80's and all the Tz's from 90's onwards have a guillotine-based system.

@@mohba01 what are the advantages of guillotin type?

Depends on the type of the system. The one used by Yamaha (ehm, Zuki and practically all others) is the purely mechanical one - position of the valve opening depends purely on engine speed. Actuator typically called "governor" is driven by the primary drive - governor translates engine speed to displacement transmitted via various levers to the valve itself. Honda just before finishing its (dirty to mother earth) two stroke program introduced sort of more advanced system, where it was controled by electric servo - adding more informations to be considered for valve opening, such as throttle opening, gear shifted and maybe some others. Bright idea, but practically it was cable wire driven and not entirely robust system to work flawless. If you are asking what the valve itself is doing inside "the engine", that is a separate story. Practically what do you want is to maximaze the time the pressure is being applied to the piston, hence to let gas expanding as long as possible increasing the engine torque, hence power at given speed. This generally improves the effeciency of rec. piston engine. Of course because it is a 2T technology, your expansion time is limited by opening the exhaust port from which it expands to exhaust - piston driving drops rapidly, it's timing is practically set by the upper edge of the exhaust port - being what is effectively changed by the valve itself. Valve is variable exhaust port top edge. As the engine is running slow, you have more time for everything, hence you can move the edge of the exhaust port down (valve goes down and closer to piston) - hence improving efficiency of the "working stroke". But as you speed goes up, the overall timing of all events is completely different and your "low positioned edge" of the exhaust port starts being exactly counter productive. Engine something like "stalls" in terms of power and you need to make you exhaust port edge higher so as exhaust dynamics can work well with respect to high engine rpm. Consequently valve goes up (and far from piston) effectively opening the exhaust port sooner. It's a pure trade off. Exactly the same situation like spark advance timing. This system has a direct counter part in 4T technology - exhaust camshaft phaser. Phaser also adjust the time when exhaust valve starts to open (effectively the time when the expansion curve is affected by the loss of gas exiting the exhaust port).

@@marekriha8992👍 , he might mean for the likes of a DTR not a YZ , if it’s a Yz then he’s better ask a factory mechanic how to gain that fraction more power ( they know best and will tell you by experience ) . As for the DT”R” then it’s well tuneable like grinding out the power valve from 10%-30% in some parts . You will have no bottom end power till 7 k ( it’s stupidly underpowered and you burn out clutches faster ) and then it comes in well more aggressive given you matched the exhaust to the exact tuned set up . At best you can turn a DTR into a supermoto ( lower to the ground and done right your going to achieve 105 -115 mph ) . But the low stoop on the front end you defo need a front fender brace before you learn that plastic mud guard try’s to fold down going into the front wheel . A good concept of the band tuning is like what you said about Honda , especially with the difference of the track NSR and the CR . Ones built for less aggressive band but longevity at high revs and the CR comes in more aggressive and pinned to long goes bang lol .

Bhul ja beta...kis jamane mein rhe rahe ho. Yamaha ne kardi launch Fz-X as Xsr . Try it out it's good as beginner bike.